block: rename BLK_EH_NOT_HANDLED to BLK_EH_DONE

The BLK_EH_NOT_HANDLED implies nothing happen, but very often that
is not what is happening - instead the driver already completed the
command.  Fix the symbolic name to reflect that a little better.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Documentation/scsi/scsi_eh.txt

@@ -97,9 +97,9 @@ function
 	This indicates that more time is required to finish the
 	command.  Timer is restarted.  This action is counted as a
 	retry and only allowed scmd->allowed + 1(!) times.  Once the
-	limit is reached, action for BLK_EH_NOT_HANDLED is taken instead.
+	limit is reached, action for BLK_EH_DONE is taken instead.
 
-    - BLK_EH_NOT_HANDLED
+    - BLK_EH_DONE
         eh_timed_out() callback did not handle the command.
 	Step #2 is taken.